Turning roofs into gardens can help agencies cut energy costs

Mar. 19, 2013 - 12:26PM
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The Morgan Processing and Distribution Center in New York City features a "green" roof, complete with gardenrs and walking paths. (U.S. Postal Service)

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In 2009, the U.S. Postal Service replaced the aging roof atop the Morgan Processing and Distribution Center in New York City with a 2.5-acre “green” roof, complete with native plants, grass and walking paths. The installation is projected to save the agency $30,000 a year in heating and cooling costs.

In 2012, the agency installed another green roof on top of its Colvin-Elmwood Post Office in Syracuse, N.Y, that will reduce heating costs and storm water runoff.

Thomas Day, the Postal Service’s chief sustainability officer, said green roofs make sense when replacing an aging roof in a dense urban setting because the vegetation absorbs rainwater and reduces groundwater runoff while providing employees with an inviting outdoor space.

“We will continue to pursue green roof projects when they make good business and environmental sense,” Day said.

As agencies focus on reducing energy use at federal buildings, they are increasingly turning to their rooftops to help them meet their goals, according to federal officials and experts.

There are two popular options for eco-friendly roofs: green and white.

A green roof consists of vegetation and grasses that absorb the sun’s rays and keep the building cool. A white roof is designed to reflect as much sunlight as possible. Both help lower heating and cooling costs by providing a protective barrier between the inside of the building and the sun.

Congress and the White House have been pressing agencies hard to invest in green buildings and eco-friendly renovations. The 2007 Energy Independence and Security Act, for example, requires agencies to reduce energy use in their facilities by 30 percent from a 2003 baseline by 2015. A 2009 executive order requires 15 percent of buildings to meet green guidelines. Newly constructed buildings must use 30 percent less energy than a typical building of the same size. Renovated buildings must use 20 percent less energy.

Chris Evans, energy manager at Sandia National Laboratory in Albuquerque, N.M., said the lab complex employs specially made roofs that reflect sunlight to reduce cooling costs. Any new or renovated building at Sandia is given a so-called “cool” roof.

The climate and lack of rainfall in the American southwest makes any “green” roof impractical, he said. Different climates require different creative roof solutions, he added.

The roofs are part of a goal at Sandia to lower the laboratory’s overall energy use by 25 percent by 2017 from a 2011 baseline.

Other federal buildings that have green or reflective roofs include:

 The Sam Nunn Federal Center in Atlanta has two green roofs and another white roof that have helped lower its energy bill by 23 percent.

 The Peace Arch Land Port of Entry in Blaine, Wash., has a 22,000-square-foot green roof.

Dirk Meyer, a General Services Administration buildings expert, said the agency looks to maximize the life and value of its roofs — through reflective material or with vegetation — wherever possible.

“The durable roofs are a sound investment that can reduce our operation and maintenance costs, minimize replacement costs, and protect the value of our building assets over the long haul,” Meyer said.

John Molesky, the coordinator for the League of Green Embassies, an organization of American embassies that work to promote environmental and energy-saving solutions, said U.S. embassies are increasingly part of the push to use highly reflective roofs. One example is the new Innovation Center at the U.S. Embassy in Helsinki, Finland.

“We look at sustainability from a business perspective: What are the high-performance solutions that provide the peak returns on investment and minimize taxpayer expenses?” Molesky said.